For all those "Techies" on the list - PCM Calculations (PW%)

From: Bernd D. Ratsch (bernd@dodgetrucks.org)
Date: Mon Feb 12 2007 - 13:00:43 EST


Ok, I know some of us really don't care about this, but others do think
about this from time to time for tuning calculations.

Here's how the PCM determines the Injector Pulse Width (SBEC/JTEC and NGC
I/II/III).

Pulse Width is determined by 4 factors:

Load x Base PW x O2 x Adaptives

SBEC/JTEC PCM

(RPM/Max RPM) x (MAP Baro) x (TPS x ECT x IAT x Sensed Battery Voltage x
LTFT) x (Upstream O2) x (STFT x LTFT) = PW

NGC I/II/III & GPEC PCM

(RPM/Max RPM) x (T-MAP Baro x EGR*) x (TPS x ECT x IAT x Sensed Battery
Voltage x LTFT) x (Upstream O2) x (STFT x LTFT x Purge Vapor Ratio) = PW

* If equipped

So...there youhave it. Put that into your spreadsheet and viola...you now
know the base Injector Pulse Width.

Granted, there's a bit more to the LTFT and STFT values, but that's the
basics.



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